1. Field of the Invention
The present invention relates to a method for producing a frame-attached transparent plate applied to, for example, a fixed window of an automobile, and an apparatus used for producing such frame-attached transparent plate.
2. Discussion of the Background
A fixed window 30 provided at a side face of an automobile is often formed by fitting a frame-attached glass plate 33 to a recessed opening portion 32 of a body panel in order to form a flush surface in the automobile body and to improve the appearance (FIG. 3).
The frame-attached glass plate 33 comprises a frame 35, called under the name of a gasket, a mole, a molding or the like, attached to a peripheral portion of a rear surface 34A (an inner side of an automobile) of a glass plate 34. The frame-attached glass plate 33 is fixed to the body panel 31 with an adhesive agent 36. On the rear surface 34A of the glass plate 34, a dark-colored coating layer 37 by ceramic coating is provided so that the adhesive agent 36 is not visible from a side of the front surface 34B (an outer side of automobile).
In many cases, the glass plate 14 is bend-shaped in a two-dimensional direction or a three-dimensional direction.
The following methods are used for producing the frame-attached glass plate 33: conventional example 1 is a bonding method where a frame 35 is formed by bonding an elongated extruded material formed by extruding to a glass plate 34 by means of a double-coated tape; and conventional example 2is a one-piece injection-molding method where a frame 35 is formed by injection-molding resin on a peripheral portion of a glass plate 34 placed in a predetermined mold.
In the conventional example 1, however, the shape in cross section of the frame 35 is constant due to the extruded material, and there is apt to occur a poor appearance derived from a poor dimensional accuracy, a poor bonding strength or a curve in the extruded material. Such poor appearance appears remarkably when a degree of curving in the glass plate is large. In order to eliminate the poor bonding strength in the extruded material, it is considered appropriate to use an adhesive agent such as urethane sealant or the like. However, use of the adhesive agent creates new problems that a post treatment for removing a squeeze of the bonding agent is necessary, and it takes time for the solidification of the bonding agent.
The conventional example 2, although it can eliminate the problems in the conventional example 1, creates a problem in that the cost for manufacturing is high. In particular, it is necessary to increase the accuracy of the shape of the mold in order to place the glass plate in the mold. When the accuracy of the shape of the mold is low, the glass plate is broken at the time of one-piece injection-molding of the frame. Further, in a case of using a curved glass plate, an error in the curved shape takes place in the glass plate. When a degree of curving in the glass plate is large, the error in the curved shape appears remarkably. When the error in the curved shape appears remarkably, the glass plate is broken at the time of one-piece injection-molding of the frame even though the accuracy of the shape of the mold is high.
Further, there is proposed a method for producing a panel for an automobile wherein a gasket main body of substantially annular shape is formed by injection-molding in a mold, the mold is opened, and a glass plate is pushed toward the opened mold to bond the gasket main body to the glass plate (U.S. Pat. No. 5,443,673), which is conventional example 3.
In the conventional example 3, after the gasket main body has been obtained by injection-molding, the glass plate is pushed to the gasket main body in a state that the gasket main body is held in the mold. Accordingly, if the shape of parting surfaces of the mold, after the mold has been opened, does not meet the shape of the glass plate, the glass plate is broken when the glass plate is pushed. On the contrary, a fault of bonding of the gasket main body to the glass plate may occur. In particular, when the gasket main body is provided on only one surface of the glass plate(herein-below, the one surface is referred to as a surface), the fault of bonding is serious unlike a case that the gasket main body has the following structure.
Namely, there has been known such a structure that a recessed portion adapted to receive an edge and both faces of the glass plate is formed in the gasket main body, and the gasket main body is attached onto the glass plate in a state that the periphery of the glass plate is inserted in the recessed portion. The presence of the recessed portion in the gasket main body reinforces a holding strength between the gasket main body and the glass plate when the gasket main body is fitted to the glass plate. However, when the gasket main body is provided on only a surface of the glass plate, the holding strength to the both members depends on the bonding of these members. Accordingly, the above-mentioned poor bonding strength appears remarkably as a problem in a case of providing the gasket main body on only a surface of the glass plate.
When the glass plate is bend-shaped, in order to prevent the breakage of the glass plate, it is necessary to form previously parting surfaces of a mold to have a circular arch plane or spherical plane which corresponds to a curved shape of the glass plate, and to determine correctly the relative position of the glass plate and the gasket main body. Accordingly, there are problems that cost for the mold is high and steps for manufacturing are complicated.
It is an object of the present invention to provide a method for producing a frame-attached transparent plate wherein the shape in cross section of a frame can optionally be selected even when the transparent plate such as a glass plate is bend-shaped; a poor dimensional accuracy, a poor bonding strength and a poor appearance of the frame can be eliminated as well as the cost for the mold can be reduced, and the frame can be provided on a surface of the transparent plate without complicating the steps for manufacturing.
Further, it is another object of the present invention to provide an apparatus used suitably for the method for producing a frame-attached transparent plate.
In order to achieve the above-mentioned objects, the present invention is to provide a method for producing a frame-attached transparent plate formed by bonding a frame to a peripheral portion of a surface of a transparent plate, the method for producing a frame-attached transparent plate being characterized by comprising injecting a resinous material into a cavity space formed in a mold, which has a shape corresponding substantially to the shape of a frame, to form the frame; opening the mold to expose outside at least a surface to be bonded to the transparent plate, of the frame; arranging the transparent plate to oppose to the frame; projecting the frame from the mold so as to correspond to a curved shape formed in a peripheral portion of the transparent plate to thereby press the frame to a surface of the transparent plate, and bonding the frame onto the peripheral portion of the transparent plate.
In this method for producing a frame-attached transparent plate, the shape in cross section of the frame to be molded in the mold can optionally be selected and a poor dimensional accuracy, a poor bonding strength, and poor appearance and so on do not occur.
Further, in the method for producing a frame-attached transparent plate, the frame is projected for bonding from the mold in correspondence to a curved shape in the periphery of the transparent plate. Accordingly, a mold in which parting surfaces are flat or nearly flat in shape can be employed even when the transparent plate is bend-shaped, and the determination of the relative partitions of the transparent plate and the frame can be simplified in comparison with the conventional techniques.
Namely, in the method for producing a frame-attached transparent plate, the above mentioned objects of the present invention, e.g., the reduction of cost for the mold, the simplification of steps for manufacturing, can be achieved.
In this case, it is preferable that a pushing means capable of projecting and retracting with respect to a parting surface of the mold is provided in the mold, and the frame is projected by means of the pushing means. According to the method for producing a frame-attached transparent plate, for example, a frame formed in a flat state can be certainly and continuously bonded to a curved plane of a transparent plate.
Further, in the method for producing a frame-attached transparent plate, it is preferable to project the frame with a plurality of pushing pins independently from the mold. According to the method for producing a frame-attached transparent plate in which each of the pushing pins can be projected independently, various types of transparent plates having different curvatures can be treated by determining suitably and separately dimensions of projection on each of the pushing pins.
In the method for producing a frame-attached transparent plate of the present invention, it is preferable that in order to increase a bonding strength between the frame and the transparent plate, a preliminary bonding is conducted by pressing the projected frame to a surface of the transparent plate, and a primary bonding is conducted by pressing the preliminarily bonded frame to the transparent plate.
Further, the present invention provides an apparatus comprising a mold for a frame-attached transparent plate, which has a cavity space having a shape corresponding substantially to the shape of a frame to be attached to a peripheral portion of a surface of a transparent plate of a frame-attached transparent plate and into which a resinous material is injected to form the frame, the apparatus used for producing a frame-attached transparent plate being characterized in that a large number of pushing pins are arranged with predetermined intervals along a continuing direction of the frame so as to be projected and retracted with respect to parting surfaces of the mold wherein the pushing pins are disposed so that they press the frame toward the transparent plate when the mold is opened so that the transparent plate is opposed to the frame, and that the length of projection of each of the pushing pins can be selected.
In this case, it is preferable that the length of projection of each of the pushing pins can be selected depending on a curved shape of the periphery of the transparent plate.
Since the mold for the apparatus used for producing a frame-attached transparent plate is provided with a plurality of pushing pins which can project and retract with respect to parting surfaces of the mold, the frame can certainly and easily be bonded to a transparent plate having a curve even in a case that the parting surfaces are formed to be flat or nearly flat. Further, universality is obtainable with respect to various kinds of transparent plates having different curvatures by selecting separately the length of projection of each of the pushing pins.
In the method for producing a frame-attached transparent plate or the apparatus used for the method according to the present invention, it is preferable to provide such a construction that the parting surfaces of the mold are held in a horizontal state and the frame is projected in a vertical direction. In this case, it is further preferable to provide such a construction that the transparent plate is arranged above the frame to oppose to it, and the frame is projected upward.
In a case that the parting surfaces are maintained in a vertical state and the frame is projected in a horizontal direction, there may be a disadvantage that the frame deflects due to its dead weight or a disadvantage that it drops. In order to prevent such disadvantages, it is necessary to add separately a special means to hold the frame. On the other hand, in a case that the frame is projected downward in a vertical direction to press it to the transparent plate, it is enough to add an engaging means to prevent the frame from dropping from the mold when the mold is opened. Further, in a case that the frame is projected upward in a vertical direction to press it to the transparent plate, it is unnecessary to provide a special means for holding the frame or an engaging means for holding the frame. In this case, the frame can be projected toward the transparent plate by only pushing a lower surface of the frame.
In the present invention, the cavity space in the mold has a shape corresponding substantially to the shape of the frame. The word xe2x80x9csubstantiallyxe2x80x9d has the following meaning. Namely, when a resinous article is formed by injection-molding, the shape of the resinous article usually becomes slightly large when the resinous article has been taken out from the mold. This phenomenon is due to a release of pressure caused by releasing the resinous article from the mold. Accordingly, the cavity space formed in the mold is slightly smaller than the shape of the resinous article to be obtained. In this description, xe2x80x9csubstantiallyxe2x80x9d means that the shape of the cavity space is determined in consideration of a change in the shape of the frame to be obtained.
In the present invention, it is useful to form the parting surfaces of the mold into a flat shape or a nearly flat shape. Namely, the formation of the parting surfaces having a flat or nearly flat shape can minimize error in designing the mold as well as reducing cost for manufacturing the mold. According to the method of the present invention, when the parting surfaces are made flat or nearly flat in shape, certainty and easiness do not sacrifice for the bonding of the transparent plate to the frame. Accordingly, it is useful to form the parting surfaces of the mold to be flat or nearly flat. There is an advantageous case that the parting surfaces of the mold have a curved shape, from another viewpoint. Description on this point will be described after.
In the description, a passage xe2x80x9cparting surfaces of a moldxe2x80x9d has the meaning as follows. First, description will be made as to the mold used for molding the frame. The mold for molding the frame comprises a pair of molds (the first mold and the second mold) as basic structural elements. Contacting surfaces between the first mold and the second mold, i.e., surfaces defining the border of these molds, when opened, are parting surfaces. Predetermined projections and recesses are formed in the first mold and/or the second mold at positions in the parting surfaces of the mold. A cavity space is formed by the projections and recesses. It is possible to constitute the mold with three or more number of molds.
The frame molded in the cavity space of the mold is bonded to a peripheral portion of the transparent plate. Since the frame is projected from the mold toward the transparent plate, the shape of the mold is such that operations for projecting the frame are not hindered. Accordingly, a surface (which is in fact a surface located in the cavity space, and a portion at which the pair of molds do not contact) which corresponds to a surface in the frame (the bonding surface of the frame) to which the transparent plate is attached, contributes the operations for projecting the frame.
In the description, the shape of xe2x80x9cparting surfaces of the moldxe2x80x9d can be considered as substantially the same as the shape of the bonding surface of the frame. Further, the bonding surface of the frame may be an inclined surface depending on the shape (a curved shape) of the transparent plate. Therefore, the bonding surface of the frame may not be a single surface. Accordingly, a way of thinking that a surface formed by a centerline along a longitudinal direction of the frame stands for the bonding surface of the frame does not miss the point. Accordingly, xe2x80x9cparting surfaces of the moldxe2x80x9d can be considered to be substantially the same as the shape of a surface formed by a centerline along a longitudinal direction of a frame. The parting surfaces of the mold being flat implies that a surface defined by the centerline along a longitudinal direction of the frame is flat.
In this description, xe2x80x9ca nearly flat shapexe2x80x9d means as follows. Namely, it is ideal that the parting surfaces are flat in order to reduce cost for manufacturing the mold and to reduce error in designing the mold. Therefore, it is desirable that the parting surfaces are flat if the frame to be projected toward the transparent plate can sufficiently follow a peripheral portion of the transparent plate.
On the other hand, since there are a large variety of shape on the transparent plate, there is a case that the transparent plate has a large curve. When the degree of curving is too large in the transparent plate, it is difficult for the frame to follow the peripheral portion of the transparent plate. In the case that a degree of curving of the transparent plate is large, it is effective that the parting surfaces are slightly curved so that the frame can follow the peripheral portion of the transparent plate. In forming curved parting surfaces, however, a degree of curving in the parting surfaces may be smaller than a degree of curving in the transparent plate. Accordingly, terms xe2x80x9cnearly flatxe2x80x9d in the parting surfaces mean that a degree of curving is nearly flat in comparison with a degree of curving in the transparent plate having a larger degree of curving. This means that a surface defined by the centerline along a longitudinal direction of the frame has a curved shape and shows a nearly flat shape.
The method for producing a frame-attached transparent plate and the apparatus used for the method for producing according to the present invention are useful in a case that a frame is bonded to a transparent plate having a curved shape. The reason is that even when the transparent plate is curved as described above, the parting surface of the mold can be formed to have a flat or nearly flat shape. Further, when the transparent plate is curved, a concave surface of the transparent plate is preferably arranged to oppose to the frame. The reason is as follows.
In a case of using the transparent plate for an automobile window, the concave surface of the transparent plate is often directed to an inner side of the automobile. In the arrangement of the concave surface of the transparent plate to oppose to the frame, a pushing force of the frame to the transparent plate is in a direction from an inner side of the automobile to an outer side of it in the arrangement of the frame in the automobile. Accordingly, the pushing force of the frame is applied to the surface at an inner side of the automobile. Even though there causes a poor appearance in a front surface due to the pushing force of the frame, such poor appearance of the front surface can not be seen from an outer side of the automobile. Accordingly, it is preferable to dispose the concave surface of the transparent plate to oppose to the frame.
In the present invention, the frame is projected in correspondence to a curved shape in a peripheral portion of the transparent plate.
In the description, xe2x80x9ccorresponding to a curved shape in a peripheral portion of the transparent platexe2x80x9d means as follows. When the transparent plate is curved, a peripheral portion of the transparent plate is formed to have an arch-like shape. Accordingly, it is ideal to project the frame in an arch-like shape so as to follow the arch-like shape of the peripheral portion of the transparent plate. In order to project the frame in an arch-like shape, it is preferable to form a pushing means to project the frame in an arch-like shape.
On the other hand, the frame can be bonded to the transparent plate even though the frame is not projected in an arch-like shape. Namely, the frame can be bonded to the transparent plate when a shape obtained by projecting the frame is rendered to be a shape formed by a group of chords which is close to an arch. In this case, the number of chords should be increased in order to bring the group of chords closer to the arch. By increasing the number of chords, a high bonding strength can be obtained (an arch is produced by increasing infinitely the number of chords). Accordingly, xe2x80x9ccorresponding to a curved shape of a peripheral portion of a transparent platexe2x80x9d means that the frame is projected so as to follow an arch defined by the peripheral portion of the transparent plate or to constitute a group of chords which approximates an arch. In the consideration of above, it is understood that in the description, to project the frame in xe2x80x9can arch-like shapexe2x80x9d includes such meaning that the frame is projected xe2x80x9cto provide a group of chords which approximates an archxe2x80x9d.
In a case that the parting surfaces of the mold are flat, xe2x80x9cprojecting the frame so as to correspond to a curved shape of the peripheral portion of the transparent platexe2x80x9d can be said in other words as follows. Namely, a large number of portions among all portions of the frame are selected, and the distance of projection a of each of the large number of selected portions has a predetermined distance respectively. Each of the selected portions corresponds one to one to each portion in the peripheral portion of the transparent plate opposing respectively.
On the other hand, assuming that a plane defined by chords connecting end portions of each arch (which corresponds to a comer portion of the transparent plate) of the peripheral portion of the transparent plate, the distance b between the assumed plane and each portion of the peripheral portion of the transparent plate corresponds one to one to each selected portion of the frame which corresponds one to one to a portion of the peripheral portion of the transparent plate. Accordingly, the distance of projection a corresponds one to one to the distance b. Then, the relation of a difference between in each of the distance a and the distance b is considered. The difference always takes a constant value (the distance between the assumed plane and the parting surface) in each portion of the frame. Accordingly, when the parting surfaces of the mold are flat, xe2x80x9cprojecting the frame so as to correspond to a curved shape of the peripheral portion of the transparent platexe2x80x9d can be said in other words as described above.
As described in the description of a first embodiment, the frame of the present invention can take various shapes in selection. However, in the relation of the frame to the transparent plate, the frame is formed to have a shape to be bonded to only a surface as well as its near edge of the transparent plate, or only a surface of it. It is preferable that from the viewpoint of error in dimensions of the transparent plate, the frame takes a shape to be bonded to only a surface of the transparent plate. The application of the present invention to a frame having a preferred shape can eliminate effectively a poor dimensional accuracy, a poor bonding strength and a poor appearance.